Liquid biopsy NGS as a longitudinal follow up tool in the clinical management of OSCC.

Abstract

e18156 Background: Oral squamous cell carcinoma constitutes one of the major sites of head and neck cancer. Early detection of these cancers is known to have good prognosis with surgery being the prime modality of treatment. One of the major challenges associated with oral cancer management is field cancerization, because of which recurrence is inevitable in some patients, in spite of adjuvant treatment. This pilot study aims to establish a minimal gene NGS panel on liquid biopsy, that could help in better in better stratification of OSCC patient to improve their clinical outcomes. Methods: OSCC patients with loco regionally advanced stage planned for curative intent therapy in the form of surgery following by (node positive disease), were enrolled in this study after obtaining the informed consent. As per the protocol tumor tissue from resected specimen and peripheral blood (10ml in streck tube) before the surgery and two longitudinal end points a) after 2 weeks of the surgery and the b) 3 weeks post adjuvant radiotherapy/ concurrent-chemo-radio therapy were collected. Results: A minimal 9 gene ( NFE2L2, PIK3CA, FGFR1, CDKN2A, NOTCH1, HRAS, CCND1, RB1, TP53 ) NGS panel was used to screen for mutations in OSCC patients at baseline and through the treatment journey of these patients to assess the molecular level minimal residual disease. Key findings include, (1) a 100% diagnostic yield for (Tissue) this panel as a screening tool to understand disease biology in these patients, and with 100% sensitivity (2) 63% (n=7 patients of the patients had ctDNA positive at the base line and at least one follow-up (3) one out of eleven patients demonstrated ctDNA positivity throughout the course of monitoring using liquid biopsy NGS. (4) four patients did not show any ctDNA positivity in their baseline nor at any time point subsequently. In summary, in advance stage of oral cancer patients (where bone and node were positive), ctDNA as a biomarker was able to stratify the patients as a prognostic biomarker. Conclusions: This pilot study provides a highly cost effect NGS screening panel as a tool to predict the prognosis as well as to better stratify patients at high risk of recurrence in OSCC post-surgery, using baseline tissue, baseline liquid biopsy as well as on longitudinal follow-up. Further randomized trails may be required to escalate or de-escalate treatment strategies. Validation of this panel on a larger cohort of OSCC is warranted before we could bring this tool to the clinic.